The Old Armenian translation of the Ars grammatica of Dionysius Thrax (second half of the 5th century) is considered the first translation of the Hellenistic school, with its literal rendering of the original and its language full of neologisms, artificial grammatical forms and syntactic constructions. This translation, in which the core of the Armenian grammatical terminology was created, initiated the study of the Armenian language. The translator combined the attribution of grammatical categories borrowed from Greek to Armenian, to which they are not characteristic, with the creation of artificial grammatical forms that deviate from the original and describe the real features of the Armenian language. In the period from the 6th to the 11th centuries five commentaries on Dionysius’ grammatical work were written. In the 11th century Grigor Magistros and in the 13th century Yovhannēs Erznkats‘i wrote their compilatory commentaries, incorporating the previous five into them. Grigor Magistros also retold Homer’s biography based on classical sources and narrated the citations from Homer in a broader context. Later, five more commentators — Vardan Arewelts‘i (13th c.), Esayi Nch‘ets‘i and Yovhannēs Tsortsorets‘i (both lived in the 13th–14th centuries), Aṛak‘el Siwnets‘i (14th–15th centuries) and David Zeyt‘unts‘i (late 16th c.) — wrote commentaries on the grammar of Dionysius. The article shows how different authors, retaining over the centuries the same tradition, tried to overcome the description of Armenian by means of grammatical categories non-characteristic of it.